The present invention relates to processes for hydroxylating olefins in the presence of an osmium carbonyl containing catalyst, and optional co-catalyst.
Processes for the production of glycols such as ethylene glycol, from olefins are well known in the art.
For example, it is well known from the technical literature and patents that olefins can be effectively oxidized to their corresponding diols with a strong oxidizing agent in the presence of catalytic amounts of specific osmium containing compounds, particularly osmium tetroxide.
The patent literature directed to osmium containing hydroxylation catalysts describes various osmium oxides used in homogeneous reaction systems in conjunction with specific oxidants. The primary oxide catalyst employed in these patents is OsO.sub.4, a highly volatile (B.P. 130.degree. C.) and toxic substance. Ordinarily, the toxic nature of OsO.sub.4 alone, while troublesome to some extent, could be dealt with by reasonably economic precautions. However, the combined properties of high volatility and toxicity (human tolerance is 0.002 mg/m.sup.3 of air) render this compound extremely dangerous necessitating large capital expenditures in plant safety equipment and design if one attempts to commercialize a process employing this compound as a catalyst for use in homogeneous reaction systems. It is for this reason that commercialization of OsO.sub.4 based plants has infrequently occurred in the past, if at all. If commercialization is attempted, the aforedescribed capital investment in safety equipment must reduce the profit margin on the products made by these processes.
Accordingly, it would be of extreme economic significance if alternative osmium catalysts could be identified which possess the property of low volatility and/or low toxicity (in relation to OsO.sub.4), together with processes for using the same to achieve glycol product selectivity and yield comparable to or better than the conventional OsO.sub.4 catalyst.
One important step in this direction is described in U.S. patent application Ser. No. 310,217, filed Oct. 9, 1981 of common assignee herein by R. Michaelson and R. Austin. This application discloses the use of various osmium halides and oxyhalides in the presence or absence of a wide variety of co-catalysts including those employed in the present invention.
Commonly assigned U.S. Pat. No. 4,314,088 and a continuation-in-part thereof, namely, U.S. Pat. No. 4,323,093 filed Oct. 9, 1981 by R. Austin and R. Michaelson collectively, disclose the use of various halide containing co-catalysts in conjunction with osmium tetroxide catalyst and organohydroperoxide oxidants to hydroxylate olefins. The halide containing co-catalysts include alkali and alkaline earth metal halides, hydrogen-halides, quaternary hydrocarbyl phosphonium halides, halogens, and transition metal halides.
Commonly assigned U.S. Pat. No. 4,390,739 filed Oct. 9, 1981 by R. Austin and R. Michaelson is directed to the hydroxylation of olefins using oxygen as an oxidant, a catalytically active metal oxide catalyst such as OsO.sub.4, and at least one transition metal salt co-catalyst.
Commonly assigned U.S. patent application Ser. No. 399,270 filed July 19, 1982, by R. Austin and R. Michaelson is directed to a process for hydroxylating olefins in the presence of an organohydroperoxide oxidant, as osmium containing catalyst and an organic halogenated hydrocarbon co-catalyst. The use of osmium carbonyls, while being disclosed as a suitable osmium catalyst, is not specifically claimed in conjunction with any of the halogenated hydrocarbon co-catalysts.
Commonly assigned U.S. patent application Ser. No. 394,414 filed July 1, 1982 by Michaelson and Austin, is directed to the use of carboxylate salts as co-catalysts for use in conjunction with osmium oxides as a catalyst and organohydroperoxides as oxidant to hydroxylate olefins.
Commonly assigned U.S. Pat. No. 4,413,151, filed July 14, 1982 by the inventors herein, is directed to a process for hydroxylating olefins in the presence of a supported osmium catalyst (including supported osmium carbonyls) and a co-catalyst such as those described herein. The oxidant can be any of organic hydroperoxides, H.sub.2 O.sub.2, and oxygen. The use of osmium carbonyls in the absence of a support is not claimed in this application.
The present invention is directed to the use of still another form of osmium compound which can be employed to catalyze the hydroxylation of olefins, namely, osmium carbonyls. Osmium carbonyls represent a safer, e.g., less volatile osmium compound, relative to OsO.sub.4, which can be employed for such catalysis.
While none of the prior art which applicants' are aware disclose the use of osmium carbonyls for directly hydroxylating olefins to their corresponding diols, the following patents are discussed to provide a general background of the prior art.
U.S. Pat. No. 2,414,385 discloses the use of hydrogen peroxide and a catalytically active oxide, such as osmium tetroxide, dissolved in an essentially anhydrous non-alkaline, inert, preferably organic, solvent, to convert, by oxidation, unsaturated organic compounds to useful oxygenated products such as glycols, phenols, aldehydes, ketones, quinones and organic acids. The formation of glycols is achieved by conducting the reaction at temperatures of between several degrees below 0.degree. and 21.degree. C. Such low reaction temperatures drastically, and disadvantageously, reduce the reaction rate to commercially unacceptable levels. At temperatures greater than 21.degree. C., the formation of aldehydes, ketones and acids is favored.
U.S. Pat. No. 2,773,101 discloses a method for recovering an osmium containing catalyst such as osmium tetroxide, by converting it to the non-volatile osmium dioxide form, distilling the hydroxylation product, reoxidizing the osmium dioxide to the volatile osmium tetroxide, and then recovering the same by distillation. Suitable oxidizing agents used to oxidize olefins, and re-oxidize the osmium dioxide, include inorganic peroxides such as hydrogen peroxide, sodium peroxide, barium peroxide; organic peroxides, such as t-butyl peroxide or hydroperoxide, benzoyl peroxide; as well as other oxidizing agents such as oxygen, perchlorates, nitric acid, chlorine water and the like. As with other methods of the prior art, the above process yields undesirable by-products (see col. 1, line 55) thus reducing the selectivity of the process.
British Patent Specification No. 1,028,940 is directed to a process for regenerating osmium tetroxide from reduced osmium tetroxide by treatment of the latter with molecular oxygen in an aqueous alkaline solution. More specifically, it is disclosed that when osmium tetroxide is used by itself as an oxidizing agent, or as a catalyst in conjunction with other oxidizing agents, to oxidize hydrocarbons the osmium tetroxide becomes reduced, and in its reduced form is less active than osmium tetroxide itself. Consequently, by conducting the oxidation reaction in the presence of an alkaline medium and supplying oxygen to the medium throughout the process, the osmium tetroxide is maintained in a high state of activity. The oxidation products disclosed include not only ethylene glycol from ethylene but also organic acids from such compounds as vicinal glycols, olefins, ketones and alcohols.
U.S. Pat. No. 4,255,596 is directed to a process for preparing ethylene glycol in a homogeneous singlephase reaction medium using ethylbenzene hydroperoxide as the oxidizing agent dissolved in ethylbenzene and osmium tetroxide as the catalyst. The pH of the reaction medium is maintained at about 14 by the presence of tetraalkyl ammonium hydroxide. A small amount of water can dissolve beneficially in the medium to reduce by-product formation and improve selectivity to the glycol.
U.S. Pat. No. 4,049,724 describes the preparation of glycols from alkenes and from unsaturated alcohols in an aqueous system using osmium tetroxide and specifying stable and water-soluble aliphatic hydroperoxides, such as t-butyl hydroperoxide, while a critical pH of 8 to 12 is maintained by a suitable combination of alkali metal buffering compounds. The preparation of propylene glycol utilizing t-butyl hydroperoxide is exemplified in the patent at a selectivity based on the hydroperoxide of 45%.
Japanese Patent Application No. Sho 54-145604, published Nov. 14, 1979 is directed to a process for hydroxylating olefins in the presence of OsO.sub.4, a quaternary ammonium salt such as tetraethyl ammonium bromide, and a peroxide including organoperoxides and H.sub.2 O.sub.2 as the oxidant.
U.S. Pat. No. 3,335,174 is directed to the use of water hydrolyzable Group Vb, VI-b and VII metal halides and oxyhalides (e.g., OsCl.sub.3) as hydroxylation and esterification catalysts in conjunction with aqueous H.sub.2 O.sub.2 as an oxidant. However, the process for using this catalyst requires the presence of lower aliphatic hydrocarbon acids such as formic, acetic and propionic acid as solvents. Under these conditions the reaction times vary from 1/2 to 4 hours, but at the shorter reaction times it is disclosed that substantial amounts of epoxide result. The only yield disclosed is obtained in connection with tungsten hexachloride in Example 1. This yield is extremely low, i.e., 22%, and includes both half-acetate and diol. Thus, among the major disadvantages of the process described in this patent are the low selectivities to diol and the corrosiveness of metal halides in the presence of glacial acids such as acetic acid.
See also: U.S. Pat. No. 3,317,592 (discloses production of acids and glycols using oxygen as oxidant, OsO.sub.4 as catalyst at pH 8 to 10); U.S. Pat. No. 3,488,394 (discloses hydroxylation of olefins by reacting olefin and hypochlorite in the presence of OsO.sub.4); U.S. Pat. No. 3,846,478 (discloses reaction of hypochlorite and olefin in an aqueous medium and in the presence of OsO.sub.4 catalyst to hydroxylate the olefin); U.S. Pat. No. 3,928,473 (discloses hydroxylation of olefins to glycols with O.sub.2 oxidant, octavalent osmium catalyst (e.g. OsO.sub.4), and borates as promoter); U.S. Pat. No. 3,931,342 (discloses a process for recovering glycols from an aqueous solution containing alkali metal borate and osmium compounds (e.g., OsO.sub.4)); U.S. Pat. No. 3,953,305 (discloses use of OsO.sub.4 catalyst for hydroxylating olefins which is regenerated by oxidizing hexavalent osmium with hexavalent chromium and electro-chemically regenerating hexavalent chromium); U.S. Pat. No. 4,203,926 (discloses ethylbenzene hydroperoxide as oxidant used in two-phase system to hydroxylate olefins in presence of OsO.sub.4 and cesium, rubidium and potassium hydroxides); U.S. Pat. No. 4,217,291 (discloses the oxidation of Osmium (III) to (IV) in an ionic complex with oxygen and an alkali metal, ammonium, or tetra (-lower) alkyl ammonium cation to a valency of greater than +5+organohydroperoxides); U.S. Pat. No. 4,229,601 (discloses the use of cesium, rubidium and potassium hydroxides as promoters for OsO.sub.4 catalyst and t-butyl hydroperoxide oxidant for hydroxylating olefins); and U.S. Pat. No. 4,280,924 (discloses a process for regenerating perosmate catalyst, e.g., cesium, rubidium and potassium perosmate).